Conventional television sets are being used with ever increasing frequency as a means for communicating audio and video information to the viewer. The video information may be graphical, such as a scene, chart or design, or it may be alphanumeric characters, such as numbers, letters or symbols that together convey a written message. Such alphanumeric information may take the form of news emergency warnings issued by the National Weather Service of inclement weather, or notification by the local education authorities of school closings due to snow or other causes. In addition, written news broadcasts, scores of sporting events, and stock market information are commonly transmitted via broadcast television signals or equivalent closed circuit cable transmissions.
In the present state of the art, applicants are unaware of any means by which the information contained in a conventional analog video signal may be readily converted to a binary signal for use by a computer. This would be advantageous in situations as the above described since the computer, once having information of an approaching thunderstorm for example, could automatically disconnect household appliances, such as air conditioners, which are particularly susceptible to damage during thunderstorms. The present apparatus could also be used to monitor school closings and could regulate household activities accordingly. In addition, handicapped persons, such as the blind, could benefit by the conversion of alphanumeric data transmitted over the television into a computer recognizable code which could then be output to a voice synthesizer. A further use of the invention would be in the case of an individual having a personal computer at home to update his stock market portfolio directly from the stock quotes on the television.
Although the methods and apparatus for receiving television signals, whether by broadcast or close circuit transmission, and converting them into images on the television screen are old and well known in the art, a basic understanding of the operation of a conventional television receiver is helpful. A television operates by rapidly generating a series of lines across the face of the television tube in a sequence similar to a typewriter generating lines across the face of a page. The lines are generated by scanning an electron beam across the phosphorous surface of a television tube. Each scanned line must start at a definite time and location after the preceding line to trace the scene in precisely the same manner in which the scene was originally viewed by the television camera or other signal source. Otherwise, the various lines might be skewed or out of synchronism, resulting in a badly distorted or incomprehensible picture. To ensure accurate synchronization between the television camera and receiver, synchronizing pulses are transmitted as a part of the signal.
Synchronizing and scanning circuits in the television respond to the incoming analog video signal to produce sweep signals that are applied to the picture tube by plates or coils to sweep the electron beam across the screen. The electron beam sweeps relatively slowly as it excites the fluorescent spots on the face of the picture tube to generate an image, and returns rapidly to repeat the tracing. The sweeping action and location of the electron beam are controlled by the synchronizing pulses, namely, vertical synchronizing pulses and horizontal synchronizing pulses, and the intensity of the fluorescent spots is controlled by the video signal to correspond to the intensity of the original scene. The horizontal sync pulses initiate the retracing of the beam at the end of each line and the vertical synchronizing pulses initiate the retracing of the beam at the end of each picture field to return it to the top of the screen. The video signal, horizontal sync signal, and vertical sync signal are broadcast as an analog, amplitude modulated composite signal that may be separated or decoded into its individual components.
While method and apparatus are known for converting analog signals into digital signals, the difficulty lies in generating binary data that is accurately synchronized to correspond to the synchronization of the analog signal that generates each scene on the television picture tube.
In view of the foregoing, it is an object of the present invention to provide method and apparatus for converting a conventional analog video signal carrying alphanumeric video characters into computer recognizable binary data that may be processed further as desired by a computer.
It is a further object of the present invention to provide a method and apparatus for converting a standard television analog video signal containing alphanumeric video characters into computer recognizable binary data.
It is a further object of the present invention to provide a method and apparatus for converting the analog video component of a standard television analog signal into a corresponding stream of binary data bits.
These and other objects are accomplished by generally providing a method and apparatus for converting a conventional analog video signal carrying alphanumeric video characters into computer recognizable binary data. A signal is received containing composite video information. The received signal is decoded into component signals comprising the analog video component signal, the horizontal sync component signal and the vertical sync component signal. The analog video component signal is converted into binary matrix data representing the received signal carrying alphanumeric video characters. The binary matrix data is compared with binary data representing a known character reference set to determine the character data code for the particular unknown character and uniquely identifying the same and retrieving its unique data code. The character, once identified, can be sent to a host computer for further processing as desired.